Satire plays an important role in a healthy democracy and a vital role in an endangered one. It’s timely, then, to have “Jonathan Swift: The Reluctant Rebel,” John Stubbs’s new biography of the finest satirist in the English language. That the name of the author of “Gulliver’s Travels” persists in popular vernacular — with “Swiftian” defining caustic and accomplished wit — speaks to his lasting influence. But if Swift’s satire deserves contemporary study, so does the man himself, a figure of contradiction and intellectual courage, unafraid to savage Enlightenment England and Ireland’s greatest powers.

Born in Ireland between the English Civil War and the Glorious Revolution, Swift spent his early years in England, raised by a nurse who may well have kidnapped him. After a lackluster undergraduate career, he became private secretary to the influential diplomat and writer Sir William Temple. Later, Swift was ordained, but his political writing drew the attention of Robert Harley, the Tory prime minister of England, who made Swift his chief polemicist — an 18th-century Toby Ziegler. This was a life on the knife’s edge of power, where his writing helped destroy the powerful Duke of Marlborough and led to threats: He once defused a mail bomb sent to Harley before it killed them both.

After the Tories fell, Swift returned to Ireland as dean of St. Patrick’s Cathedral. Although he never returned to front-line English politics, his satire was influential there and in Ireland. “Gulliver’s Travels,” “A Modest Proposal” and “The Drapier’s Letters” — credited with saving Ireland by defeating unfair English currency policies — made him a hero in his homeland. Stubbs (the author of a life of John Donne) reports that when England’s new prime minister, Sir Robert Walpole, proposed arresting Swift for mauling him in verse, a friend “asked him coolly ‘whether he had 10,000 men to spare’ — for that was the size of the army the government would need to take Swift from his loyal Dubliners.”

In this excellent literary biography, Stubbs draws on extensive research to contextualize Swift’s courtier’s life within the hurly-burly of 18th-century foreign and domestic politics, also inspecting Swift’s clerical life within the doctrinal struggles of the church. He studies Swift’s literary motivations and professional contradictions: a man who disavowed political parties but became a Tory operative; a fastidious, conservative priest who became “king of the mob,” rebelling against the established order with satire that delved into the stink of daily life.

Swift’s contradictions were evident in associations that extended through the ranks of society and to other major writers of the day. He was clubbable, but wouldn’t hesitate to wound a friend for perceived deficiencies of character (or housekeeping). Among his most significant attachments were his close, controversial relationships with Esther Johnson (“Stella”) and Esther Vanhomrigh (“Vanessa”). Whether these were sexual divides scholars and differentiates Stubbs’s biography from Leo Damrosch’s of 2013. Damrosch, rebutting Irvin Ehrenpreis’s claim of Swift’s asexuality, argues at length for Swift and Vanessa’s relationship being sexual. Stubbs gives the friendships due consideration, but judicious weighing of the arguments leads him to a middle ground: History doesn’t bear out an answer. “Both women might have been his lovers; however, the possibility will always remain that for Swift the thrill lay in nothing more than wordplay.”

In his early chapters, Stubbs falls into a scholar’s trap: oversharing hard-won research. He digresses too often, losing Swift in a blizzard of ancillary detail. (Do we need a description of the town where Swift’s first boss courted his wife?) That structural haze rapidly clears, however, and is redeemed by stellar prose, a firm narrative grip and nuanced historical and literary readings. Private yet performative, generous yet stingy, conservative yet rebellious, Swift was a knotty character. Stubbs brings an incisive intellect to the task of untangling him.

Correction:

A picture caption on Feb. 26 with a review of “Jonathan Swift: The Reluctant Rebel,” by John Stubbs, included an erroneous date with the engraving of Swift. The engraving represents him circa 1740, not circa 1800. (Swift died in 1745.)

James McNamara’s work has appeared in The Washington Post, The Times Literary Supplement, The Australian Book Review and other publications.